migrate pure-logic tests to vitest (phase 1)

vitest.config.ts

@@ -1,19 +1,37 @@
 import {fileURLToPath} from 'node:url'
 
-import react from '@vitejs/plugin-react'
+import babel from 'vite-plugin-babel'
 import {defineConfig} from 'vitest/config'
 
 const r = (p: string) => fileURLToPath(new URL(p, import.meta.url))
 
 export default defineConfig({
   plugins: [
-    react({
-      babel: {
+    /*
+     * esbuild handles TS/JSX transpilation; babel runs only for the lingui
+     * macro, which must be expanded in every .ts/.tsx file that uses it (not
+     * just JSX files). We deliberately omit react-compiler, reanimated/plugin,
+     * and react-native-dotenv - those matter for render semantics and
+     * native/build output, none of which our tests exercise.
+     */
+    babel({
+      include: /\.[jt]sx?$/,
+      exclude: /node_modules/,
+      babelConfig: {
+        babelrc: false,
+        configFile: false,
         /*
-         * Only what tests actually need. We deliberately omit react-compiler,
-         * reanimated/plugin, and react-native-dotenv - those matter for render
-         * semantics and native/build output, none of which our tests exercise.
+         * The plugin runs with enforce: 'pre', so babel receives raw
+         * TypeScript before esbuild strips types - it needs the TS preset to
+         * parse it. preset-typescript auto-enables JSX for .tsx filenames.
          */
+        /*
+         * Default onlyRemoveTypeImports: false so babel elides imports whose
+         * specifiers are all types (e.g. `import {type X} from '...'`).
+         * Otherwise such imports survive as side-effect imports and drag whole
+         * runtime module graphs (and their native deps) into tests.
+         */
+        presets: ['@babel/preset-typescript'],
         plugins: [
           '@lingui/babel-plugin-lingui-macro',
           '@babel/plugin-transform-class-static-block',
@@ -22,6 +40,29 @@ export default defineConfig({
     }),
   ],
   resolve: {
+    /*
+     * Mirror Metro's platform-specific resolution so Component.native.ts /
+     * Component.ios.ts win over Component.ts (matching the jest-expo/ios
+     * preset, which resolves ios then native). Without this, files like
+     * PlatformInfo/index.ts (which throws NotImplementedError) load instead of
+     * index.native.ts (which uses the stubbed requireNativeModule).
+     */
+    extensions: [
+      '.ios.ts',
+      '.ios.tsx',
+      '.ios.js',
+      '.ios.jsx',
+      '.native.ts',
+      '.native.tsx',
+      '.native.js',
+      '.native.jsx',
+      '.ts',
+      '.tsx',
+      '.mjs',
+      '.js',
+      '.jsx',
+      '.json',
+    ],
     alias: [
       /*
        * Mirror the babel module-resolver aliases (also in tsconfig.json).
@@ -29,6 +70,56 @@ export default defineConfig({
       {find: /^#\/(.*)$/, replacement: r('./src/$1')},
       {find: /^crypto$/, replacement: r('./src/platform/crypto.ts')},
 
+      /*
+       * react-native's real entry is Flow-typed and boots a native runtime.
+       * Redirect it (and deep Libraries/* subpaths some packages import) to a
+       * small stub. Aliasing at resolution time is more robust than a
+       * setup-file vi.mock, which doesn't reach imports from externalized CJS
+       * deps like @bsky.app/react-native-mmkv.
+       */
+      {find: /^react-native$/, replacement: r('./vitest/react-native-stub.ts')},
+      {
+        find: /^react-native\/.*$/,
+        replacement: r('./vitest/react-native-stub.ts'),
+      },
+
+      /*
+       * Native MMKV module - binds to a native lib and imports react-native.
+       * Stubbed so transitive importers (#/storage) load. Tests that exercise
+       * storage logic still vi.mock this with their own in-memory impl, which
+       * takes precedence over the alias.
+       */
+      {
+        find: /^@bsky\.app\/react-native-mmkv$/,
+        replacement: r('./vitest/mmkv-stub.ts'),
+      },
+
+      /*
+       * @sentry/react-native is CJS and requires react-native internally.
+       * Stubbed so modules that pull it in via #/logger load. logger.test.ts
+       * still vi.mocks it directly to assert on calls.
+       */
+      {
+        find: /^@sentry\/react-native$/,
+        replacement: r('./vitest/sentry-stub.ts'),
+      },
+
+      /*
+       * expo-application pulls in the `expo` package's native winter runtime,
+       * which does bare CJS requires that don't resolve under Vitest.
+       */
+      {
+        find: /^expo-application$/,
+        replacement: r('./vitest/expo-application-stub.ts'),
+      },
+
+      /*
+       * The bare `expo` package's entry runs the winter runtime side-effect on
+       * import (bare CJS requires that don't resolve under node). Stub it to
+       * the named exports test-reachable code uses.
+       */
+      {find: /^expo$/, replacement: r('./vitest/expo-stub.ts')},
+
       /*
        * Former Jest moduleNameMapper entries. Vite's ESM resolution may make
        * some of these unnecessary, but they're harmless and proven, so keep
@@ -72,7 +163,13 @@ export default defineConfig({
       },
     ],
   },
-  define: {__DEV__: 'true'},
+  /*
+   * Match jest's effective environment: under jest __DEV__ was true but
+   * JEST_WORKER_ID was set, so dev-only branches guarded by
+   * `__DEV__ && !process.env.JEST_WORKER_ID` took the production path. Setting
+   * __DEV__ to false reproduces that for the equivalent branches in Vitest.
+   */
+  define: {__DEV__: 'false'},
   test: {
     globals: true,
     environment: 'node',